Portable blowers are in common use by homeowners and professionals to remove debris from yards and driveways without water or other equipment such as rakes or brooms. The portable blowers can be powered by either an electric motor or a gas-powered motor. Furthermore, some of the blowers can be converted into vacuum units in which leaves or similar debris can be vacuumed into a bag or other container.
When operated as blowers, the units provide a sweeping action using a fast moving stream of air produced by an impeller rotating within the housing of the blower. The impeller draws air into the unit through an inlet and forces the air out of the unit through an outlet. An exhaust or blower tube is typically fitted over the outlet to contain the air stream to a nozzle at the end of the blower tube. The length of the blower tube typically allows a user to stand and hold the portable blower while locating the nozzle near the ground. In addition, the nozzle outlet opening is typically smaller than the outlet at the housing to increase the velocity of the air as it exits the nozzle at the end of the blower tube.
Although portable blower units provide the ability to move debris without using water, rakes, brooms, etc., they can raise issues regarding noise during use. Because the blowers are typically used outside, the noise generated by the blowers has typically been of reduced importance. With their increasing use, however, the noise generated by the blower units has been receiving heightened attention. Furthermore, the noise generated by the portable blowers is increasing as the blowers become more powerful to improve their ability to move debris.
One attempt at addressing noise generated by portable blower units disclosed in U.S. Pat. No. 5,195,208 (Yamami et al.) is directed at blowers designed to be carried on the backs of the operators. The noise produced by the blower unit is reduced by essentially placing the unit, including the motor and the blower portions, between sound absorbing sheets located on at least two sides and the rear of the unit. Although this approach may be helpful in reducing the noise generated by backpack-mounted blower units, it does not address the needs of hand-held blowers, nor does it specifically address the noise generated at the inlet of air into the housing or at the exit of air from the outlet of the housing.